chaos

Concise Oxford English Dictionary © 2008 Oxford University Press:
chaos /ˈkeɪɒs/

▶noun

• 1 complete disorder and confusion.

  ■ Physics the property of a complex system whose behaviour is so unpredictable as to appear random, owing to great sensitivity to small changes in conditions.

• 2 the formless matter supposed to have existed before the creation of the universe.

– origin C15 (denoting a gaping void): via Fr. and L. from Gk khaos ‘vast chasm, void’.